rpi_display: add backlight driver and overlay

Add a mailbox-driven backlight controller for the Raspberry Pi DSI
touchscreen display. Requires updated GPU firmware to recognise the
mailbox request.

Signed-off-by: Gordon Hollingworth <gordon@raspberrypi.org>
Add Raspberry Pi firmware driver to the dependencies of backlight driver

Otherwise the backlight driver fails to build if the firmware
loading driver is not in the kernel

Signed-off-by: Alex Riesen <alexander.riesen@cetitec.com>

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 40676be..e809c65 100644 (file)
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -248,6 +248,13 @@ config BACKLIGHT_PWM
          If you have a LCD backlight adjustable by PWM, say Y to enable
          this driver.
 
+config BACKLIGHT_RPI
+       tristate "Raspberry Pi display firmware driven backlight"
+       depends on RASPBERRYPI_FIRMWARE
+       help
+         If you have the Raspberry Pi DSI touchscreen display, say Y to
+         enable the mailbox-controlled backlight driver.
+
 config BACKLIGHT_DA903X
        tristate "Backlight Driver for DA9030/DA9034 using WLED"
        depends on PMIC_DA903X

diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 63c507c..98f1271 100644 (file)
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_BACKLIGHT_PANDORA)               += pandora_bl.o
 obj-$(CONFIG_BACKLIGHT_PCF50633)       += pcf50633-backlight.o
 obj-$(CONFIG_BACKLIGHT_PM8941_WLED)    += pm8941-wled.o
 obj-$(CONFIG_BACKLIGHT_PWM)            += pwm_bl.o
+obj-$(CONFIG_BACKLIGHT_RPI)                    += rpi_backlight.o
 obj-$(CONFIG_BACKLIGHT_SAHARA)         += kb3886_bl.o
 obj-$(CONFIG_BACKLIGHT_SKY81452)       += sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)           += tosa_bl.o

diff --git a/drivers/video/backlight/rpi_backlight.c b/drivers/video/backlight/rpi_backlight.c
new file mode 100644 (file)
index 0000000..14a0d9b
--- /dev/null
+++ b/drivers/video/backlight/rpi_backlight.c
@@ -0,0 +1,119 @@
+/*
+ * rpi_bl.c - Backlight controller through VPU
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+struct rpi_backlight {
+       struct device *dev;
+       struct device *fbdev;
+       struct rpi_firmware *fw;
+};
+
+static int rpi_backlight_update_status(struct backlight_device *bl)
+{
+       struct rpi_backlight *gbl = bl_get_data(bl);
+       int brightness = bl->props.brightness;
+       int ret;
+
+       if (bl->props.power != FB_BLANK_UNBLANK ||
+           bl->props.fb_blank != FB_BLANK_UNBLANK ||
+           bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+               brightness = 0;
+
+       ret = rpi_firmware_property(gbl->fw,
+                       RPI_FIRMWARE_FRAMEBUFFER_SET_BACKLIGHT,
+                       &brightness, sizeof(brightness));
+       if (ret) {
+               dev_err(gbl->dev, "Failed to set brightness\n");
+               return ret;
+       }
+
+       if (brightness < 0) {
+               dev_err(gbl->dev, "Backlight change failed\n");
+               return -EAGAIN;
+       }
+
+       return 0;
+}
+
+static const struct backlight_ops rpi_backlight_ops = {
+       .options        = BL_CORE_SUSPENDRESUME,
+       .update_status  = rpi_backlight_update_status,
+};
+
+static int rpi_backlight_probe(struct platform_device *pdev)
+{
+       struct backlight_properties props;
+       struct backlight_device *bl;
+       struct rpi_backlight *gbl;
+       struct device_node *fw_node;
+
+       gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
+       if (gbl == NULL)
+               return -ENOMEM;
+
+       gbl->dev = &pdev->dev;
+
+       fw_node = of_parse_phandle(pdev->dev.of_node, "firmware", 0);
+       if (!fw_node) {
+               dev_err(&pdev->dev, "Missing firmware node\n");
+               return -ENOENT;
+       }
+
+       gbl->fw = rpi_firmware_get(fw_node);
+       if (!gbl->fw)
+               return -EPROBE_DEFER;
+
+       memset(&props, 0, sizeof(props));
+       props.type = BACKLIGHT_RAW;
+       props.max_brightness = 255;
+       bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
+                                       &pdev->dev, gbl, &rpi_backlight_ops,
+                                       &props);
+       if (IS_ERR(bl)) {
+               dev_err(&pdev->dev, "failed to register backlight\n");
+               return PTR_ERR(bl);
+       }
+
+       bl->props.brightness = 255;
+       backlight_update_status(bl);
+
+       platform_set_drvdata(pdev, bl);
+       return 0;
+}
+
+static const struct of_device_id rpi_backlight_of_match[] = {
+       { .compatible = "raspberrypi,rpi-backlight" },
+       { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rpi_backlight_of_match);
+
+static struct platform_driver rpi_backlight_driver = {
+       .driver         = {
+               .name           = "rpi-backlight",
+               .of_match_table = of_match_ptr(rpi_backlight_of_match),
+       },
+       .probe          = rpi_backlight_probe,
+};
+
+module_platform_driver(rpi_backlight_driver);
+
+MODULE_AUTHOR("Gordon Hollingworth <gordon@raspberrypi.org>");
+MODULE_DESCRIPTION("Raspberry Pi mailbox based Backlight Driver");
+MODULE_LICENSE("GPL");